When called as instance method, some defaults are copied from the
object where the call is made upon.

You may either provide a Math::Polygon::Surface $surface, or a LIST
of lines. In the latter case, the first line is the $outer polygon of
the surface, and the other are all $inner enclosures: lakes. Lines
are and Geo::Line, Math::Polygon objects, or ARRAY of points.

If no projection is specified, then the projection of the first
Geo-encoded line will be used.